Trouble matching controllers to panels.

[inetdog]

mc4 is a type of connector not a type of wire. Some types of wire rated to be used outdoors are rated to deal with the sun others are not.

These days it is likely that the wire in the MC4 connector is PV wire (a type newly introduced a few years ago. That wire is rated for UV exposure, wet environment, etc. but under the NEC it must still be protected against mechanical damage (using raceway, location in a trough, etc.) once it is outside the array itself. (It still needs to be protected against mechanical damage within the array, but being on the underside of a roof mounted panel satisfies that requirement well enough for most inspectors.

[Bucho]

I had planned to jump the negative in the combiner box (which has 2 breakers from each 2 panel series to controller) across to the ground bus in the combiner box AND jump the negative terminal of the battery to another ground bus that is connected to grounding rod. Is the jumper in the combiner box redundant?

Redundant is bad, redundant causes a ground loop. Bond at your negative battery terminal.

Seems that I need to ground the negative in order for the breakers to work, or is that only for GFCI breakers?

A GFI trips if the current leaving and returning aren't equal. A circuit breaker trips if the current gets too high. Neither of those operations requires a ground wire. However, a ground wire will be required to protect against the mishap of metal components of your system becoming energized and your ground wire won't protect against that problem unless it's bonded to the negative.

Can mc4 cabling just run unprotected down from roofing into a combiner box?

mc4 is a type of connector not a type of wire. Some types of wire rated to be used outdoors are rated to deal with the sun others are not.

...AC wiring must always be in conduit.

That doesn't sound quite right.

Combiner box output goes into 1" conduit underground across and up to the controller. Would it make sense to cut the extension cables and slip the cut ends through a short piece of conduit just to keep wiring above ground level?

I'm not following what you're talking about here.

Maybe put some sort of bushing or something on the top end so the cables don't get frayed.

http://www.lowes.com/Search=electrical+conduit+fittings

[plantian]

Update

Do you? I mean people brand new to offgrid can have unrealistic expectations about how much they're willing to do without in which case some expandability is good. But you've been doing this for quite a while right, you should have a good sense of what you do and do not need.

If you need 8 batteries, don't you need them now? If you only need 4 batteries what's the point of having 8?

No, you're right, based on the calculations I don't need them right now but it'd be nice to charge battery powered power tools rather than having to take them off the site to charge them. I can always dream. Although after seeing the 45A morning star I should have got the 30A like you said. This thing is __HUGE__, its like 3 times the size of the smaller 12v 25A controllers I have. I can't even fit it into the box I have because now reading the manual it needs 6 inch clearance above and below and its indoor rated. The inverter is also even bigger. Its like 4 times the size of the 1500 Watt 12v inverters I have. I have no idea why that is. Maybe the other one is a fake pure sine 12v?

Looks like wiring AC wires coming out of conduit into a male plug is going to work but it sure looks like garbage. I think for the next iteration I need to do that inlet you originally proposed. It would be like a million times cleaner.

Had a few questions if anyone has time:

I had planned to jump the negative in the combiner box (which has 2 breakers from each 2 panel series to controller) across to the ground bus in the combiner box AND jump the negative terminal of the battery to another ground bus that is connected to grounding rod. Is the jumper in the combiner box redundant? Seems that I need to ground the negative in order for the breakers to work, or is that only for GFCI breakers? The inverter manual says it expects a negative grounded system by default so I think the battery terminal grounding is needed.

Can mc4 cabling just run unprotected down from roofing into a combiner box? The combiner is about 5 feet off the ground on the stand-alone panel wood skeleton structure. Seems that is normal but so odd considering how AC wiring must always be in conduit. Combiner box output goes into 1" conduit underground across and up to the controller. Would it make sense to cut the extension cables and slip the cut ends through a short piece of conduit just to keep wiring above ground level? Maybe put some sort of bushing or something on the top end so the cables don't get frayed.

Thanks.

[Bucho]

So when I upgrade I need to get 8 new batteries.

Do you? I mean people brand new to offgrid can have unrealistic expectations about how much they're willing to do without in which case some expandability is good. But you've been doing this for quite a while right, you should have a good sense of what you do and do not need.

If you need 8 batteries, don't you need them now? If you only need 4 batteries what's the point of having 8?

[SunEagle]

Ha of course. Well I think the batteries have been replaced 1 at a time for 10 years or so. But I understand this reasoning to not do that. Solar sure isn't easy. So when I upgrade I need to get 8 new batteries.

Replacing "bad" batteries one at a time with a "new" one is almost akin to removing one "rotten" apple from the bunch and putting in a new one. Unfortunately the other apples have already started to turn "bad" which will affect the new one you just added. It's a PIA but that unfortunately is how physics and batteries work.

[plantian]

Yeah I was worried you were headed in that direction, that's not a good idea:

Ha of course. Well I think the batteries have been replaced 1 at a time for 10 years or so. But I understand this reasoning to not do that. Solar sure isn't easy. So when I upgrade I need to get 8 new batteries.

[Bucho]

Yes the 45A controller is overkill right now. The 1000W inverter is also too much. I have 8 batteries right now, but I'm only going to use 4 of them, 6v each, to create 24v system (as recommended earlier). If I later bring the other 4 back in to double my capacity and then double my panels then I would be able to utilize the charge controller right? Then the 1000W inverter would also be more appropriate.

Yeah I was worried you were headed in that direction, that's not a good idea:

11. Can I do a partial replacement of my flooded batteries?
We do not recommend partial battery replacement of flooded battery banks. The behavior of batteries during discharging and charging varies throughout their lifespan and if all the batteries are the same age, than they all will have similar responses. The danger with replacing only one battery is that the older batteries tend to require more charge than newer batteries, and since the new batteries are in the same circuit, they too will be overcharged. There is also the chance that the older batteries will be undercharged since the overall voltage response of all the batteries (old and new) will not be a good representation of either group. The charging system might erroneously think that ALL the batteries have reached the desired voltage and it may stop the charging of the batteries prematurely.

[plantian]

Remember that you want to stay below c/8 which is 29 A. 800 watts might be a bit much *shrug*. But you certainly won't be able to use all of that 45 amp charge controller.


Laser or inkjet?

2 inkets, one is a fax/scanner combo

Yes the 45A controller is overkill right now. The 1000W inverter is also too much. I have 8 batteries right now, but I'm only going to use 4 of them, 6v each, to create 24v system (as recommended earlier). If I later bring the other 4 back in to double my capacity and then double my panels then I would be able to utilize the charge controller right? Then the 1000W inverter would also be more appropriate.

[Bucho]

Also after looking at enclosures and how I might put the inverter and CC in boxes, I think it might make more sense for me to just bring conduit into a box, directly wire romex from the conduit into a male plug end, like http://www.amazon.com/Leviton-5266-C.../dp/B001V9LBSY , and then plug that into the inverter, all in the box. Otherwise I either have to shove a plug and extension cord into one of these boxes or have the extension cord come out exposed and then go to the inlet somewhere. The spot I have to put the gear is under an overhang but is probably considered outdoors. Then I have the "romex plugs" on the inverter's GFCI and everything would be in conduit or a box, except for the monster battery cables. Does this make sense?

How was it done before? The charge controller and especially the inverter are components that you want close to the batteries, not in a separate building.

[Bucho]

Yeah I think 1000W would be over what I need right now, but if I had 2 more panels later then it would be okay.

Remember that you want to stay below c/8 which is 29 A. 800 watts might be a bit much *shrug*. But you certainly won't be able to use all of that 45 amp charge controller.

So I think that is around what I'm looking at. I think 600W would be enough based on the devices I have, although printers seem to surge from what I've read so that is hard to tell.

Laser or inkjet?

[Bucho]

The original inverter I looked at had a 20A internal fuse so I was trying to be consistent. Does it make sense to count on the inverter to protect the wiring?

The inverters you've been looking at are made to do just that, they have overload and short protection built in. You could certainly get a breaker panel for under $30, if you're back to 15 A that's a couple bucks for a breaker going in and a couple more for at least one more coming out just to have something to put a wire on but what would that get you? That protection's already in the inverter.

Now you could use a gfi breaker thus gaining additional protection over some of the inverters you're looking at but I've already mentioned 3 ways to get gfi protection more cheaply. You could get a combination AFI/GFI breaker *shrug*.

[plantian]

Finding a 1ft 20 amp cord is easy just check amazon. At 20 amps you obviously won't be able to use the particular inlet I suggested but there are plenty of options out there. I know I've come across a 20amp inlet with a built in fuse before which sounds like just the sort of thing your looking for.

The original inverter I looked at had a 20A internal fuse so I was trying to be consistent. Does it make sense to count on the inverter to protect the wiring?

Also after looking at enclosures and how I might put the inverter and CC in boxes, I think it might make more sense for me to just bring conduit into a box, directly wire romex from the conduit into a male plug end, like http://www.amazon.com/Leviton-5266-C.../dp/B001V9LBSY , and then plug that into the inverter, all in the box. Otherwise I either have to shove a plug and extension cord into one of these boxes or have the extension cord come out exposed and then go to the inlet somewhere. The spot I have to put the gear is under an overhang but is probably considered outdoors. Then I have the "romex plugs" on the inverter's GFCI and everything would be in conduit or a box, except for the monster battery cables. Does this make sense?

I was looking at putting the inverter in a box like this:

http://www.amazon.com/Aluminum-Electrical-Battery-Enclosure-Plate/dp/B00MYI4TV2

So then I have 2 romex wires in one gland, then 1 ground and 2 battery cables going out the other gland. Hard to tell the size of the glands, maybe they are just for minor power cords and telecommunication wiring?

It's also possible to get an extension cord with a built in gfi or to get a gfi such as this that you could hardwire inline to the inverter Mike's talking about:

http://www.amazon.com/Tower-Manufacturing-30396500-08-Attachable-Manual/dp/B0049B3DIW/ref=sr_1_1?s=industrial&ie=UTF8&qid=1440451489&sr=1-1&keywords=Inline+GFCI

Yet another option is to wire a gfi outlet in that retail kiosk prior to the 20ft underground run.

P.S. It seems like the size of your inverter is moving around a lot, if you could calculate what you need that would be best.

Yeah I think 1000W would be over what I need right now, but if I had 2 more panels later then it would be okay. So I think that is around what I'm looking at. I think 600W would be enough based on the devices I have, although printers seem to surge from what I've read so that is hard to tell.

[Bucho]

@Bucho Running a 1' or less power cord from the inverter outlet to an inlet that goes through a conduit to an outlet would be perfect. Thanks for the idea. But not sure I can find a cord that small that has 20 AMP rating to match surge rating of 1500watt inverter.

Finding a 1ft 20 amp cord is easy just check amazon. At 20 amps you obviously won't be able to use the particular inlet I suggested but there are plenty of options out there. I know I've come across a 20amp inlet with a built in fuse before which sounds like just the sort of thing your looking for.

@Mike90250 I might check that inverter out although I like the GFCI protection on the outlets of this other inverter, so using an inlet works although is a bit wonky.

It's also possible to get an extension cord with a built in gfi or to get a gfi such as this that you could hardwire inline to the inverter Mike's talking about:

http://www.amazon.com/Tower-Manufacturing-30396500-08-Attachable-Manual/dp/B0049B3DIW/ref=sr_1_1?s=industrial&ie=UTF8&qid=1440451489&sr=1-1&keywords=Inline+GFCI

Yet another option is to wire a gfi outlet in that retail kiosk prior to the 20ft underground run.

P.S. It seems like the size of your inverter is moving around a lot, if you could calculate what you need that would be best.

[radareclipse]

Tagged for later.

[paulcheung]

I suspect he's thinking about the underground wire which may or may not have been abused for a decade, not his printer or whatever small electronics he's plugging in. In which case a gfi on the far end won't do a thing for him.

If that is the case, install the GFCI on the inverter side.